The present invention relates to an electrophotographic copier, facsimile transceiver, printer or similar electrostatic recording apparatus and, more particularly, to means incorporated in a developing device for transporting a developer or a toner to the surface of an image carrier.
It has been customary with a developing device to transport a developer or a toner deposited on the surface of a developing roller to a latent image electrostaically formed on an image carrier, i.e., photoconductive element by rotating the developing roller. In this sense, the developing roller plays the role of developer transporting means. After the development, the developer or the toner remaining on the photoconductive element is collected in the developing device and again transported to the photoconductive element by the developing roller. A problem with such a construction is that part of the toner enters the clearances between the developing roller and the side walls of the developing device which support the roller due to the rotation of the roller. This part of the toner rubs against the developing roller and side walls and binds, disturbing images to be formed. Moreover, when the developing roller is implemented as a sleeve accommodating a magnet roller therein, the sleeve generates eddy current as it moves across the magnetic field of the magnet roller. The eddy current is apt to increase the torque acting on the developing roller and to cause the toner to melt in the developing device because of heat generated in the roller.